General Comments

This manuscript details an examination of two different hydrodynamic models

(ADCIRC and NEMO) and their applications in modeling of storm surge due to

tropical cyclones. Tropical cyclones were modelled both using ERA5 wind

reanalyses and a selection of parametric wind models. Sensitivies between ADCIRC

and NEMO, as well as sensitivities to wind model and drag law, are evaluated.

The results of the various experiments indicate that storm surge, defined as the

non-tidal residual in this study, are relatively insensitive to the use of

ADCIRC vs NEMO. However, there are some differences when comparing wind product

used. This study shows that the reanalysis winds generally outperform the

parametric wind models.

Overall, I believe that this manuscript presents some useful information with

regards to modeling storm surge caused by tropical cyclones. The experiments

were clearly carefully designed to examine the sensitivities of interest. The

combination of an inter-model as well as an intra-model comparison was

particularly interesting. I do have some comments regarding scientific questions

and experiments as detailed in the "Specific Comments" section; however, I think

the scientific merit of this manuscript is generally sound.

While the manuscript as a whole is generally interesting and explores some

useful/impactful questions, there are numerous grammatical/typographical issues

that make the story told hard to follow. I have detailed some specific examples

of readability issues in the "Technical Corrections" section; however, these

examples should not be taken to be a comprehensive list of typographical

problems. I strongly suggest a thorough editing of the manuscript to improve

readability and accessibility.

I recommend major revisions, primarily related to presentation quality, and

look forward to reading a revised version of this manuscript.

Specific Comments

Section 2

When describing the selection of tide gauges used in the evaluation of storms

you note that you select gauges that are within a 300 km radius of the hurricane

in lines 91-92. In lines 95-96 you note that gauges registering storm surges of

less than 15 cm are also excluded. Why not simply use the surge-based criteria

alone rather than also having the distance criteria? I just find the distance

criteria to be rather arbitrary whereas the surge criteria (assuming you base

the selection off of observations instead of model results) is more rational.

When describing the parametric wind models in lines 108-126, you do not touch on

the various parameters within each model and what you set them to. For example,

in the Chavas et. al. (2015) model there are several parameters that need to be

prescribed by the user. Among these are the radiative-subsidence rate (W_cool),

surface drag coefficient (C_d), and the ratio of enthalpy and momentum exchange

coefficients (C_k/C_d). The other parametric wind models also have

user-prescribed coefficients. You do not touch on what values you selected for

these parameters. I think it would be useful to add a subsection to Section 2

where you give a short description of each parametric wind model and the values

you selected in order to make the experiments herein more reproducible by

others.

Section 3

When describing the numerical grids of ADCIRC vs NEMO in Section 3.1, you do not

note the total number of degrees of freedom of the two grids. While it is not

front and center in the manuscript, you do provide wall-clock times in the

appendix. Without knowing the number of mesh vertices it is hard to get a sense

of the true computational cost/how it will scale with more computational power.

Section 4

In lines 276-277 you note that, "ADCIRC simulations tends to underestimate the

maximum [storm surge] compared to tide gauge data." Could you compute the mean

error in addition to the mean absolute error to give a sense of the differences

between NEMO and ADCIRC in this regard? It is hard to quantify based off of

Figures 4 and 5 alone without hard numbers. Using the mean error would allow for

the performance to be quantifiably evaluated instead of qualitatively. In the

discussion at line 437, you also note that, "[i]n general, both models

underestimate the storm surge amplitudes."

You note in lines 351-355 that different parametric wind models perform are best

for different storms. I feel that this might relate to the selection of

parametric wind model parameters. While I do not think you need to do a

sensitivity analysis of the wind model parameters (although you could), I think

it is worth noting that this may be part of the issue.

In lines 357-359 you say that the parametric wind models underestimate more than

ERA5, could this be due to the far-afield winds not being captured in the

parametric models? Does this underestimation go away if you only look at

stations, for example, within the 30 knot wind radius of the center of the

storm?

Section 6

I think that adding a description of future work would be quite valuable. For

example, NEMO lacking wetting/drying capability will drastically limit its

usefulness as a storm surge prediction model due to lack of ability to capture

inundation of floodplains. I assume that adding a wetting/drying algorithm is

part of future work but it might be useful to state here. Additionally, I think

it might be useful to compare the computational performance of NEMO vs ADCIRC,

especially since the manuscript highlights the usefulness of NEMO in simulating

storm surges.

Technical Corrections

Lines 22-34: This paragraph is hard to follow. It seems to try and

highlight two different things: 1) how tropical cyclones cause storm surge, and

2) the four storms evaluated in this manuscript. While I was able to understand

the message of the paragraph, I had to read the whole thing two or three times

to truly parse what was being communicated. As an example, rather than saying,

"Wilma is the most intense Atlantic hurricane by lowest pressure on record,

formed on October 15, 2005, reaching sustained winds of 295 km/h before making

landfall in southwestern Florida on October 24, 2005.", it would be more clear

to write something along the lines of, "Hurricane Wilma, which formed on Ocober

15, 2005 and made landfall in southwestern florida on October 24, is the most

intense Atlantic hurricane on record as measured by atmospheric pressure." I

think if might be useful to separate the description of each storm at the very

least into multiple sentences. Another approach would be to remove the explicit

storm descriptions and instead add more of the detail to Table 1.

Lines 54-56: In the sentence starting with, "Parametric wind models," the clause,

"enable to compute a large number of simulations," is grammatically incorrect.

Line 64: Another study that looks at the inclusion of baroclinicity in

evaluating storm surge is Pringle et. al., 2019

(doi:https://doi.org/10.1029/2018JC014682).

Lines 100-102: You describe ERA5 as having a resolution of 0.25 degrees and

ERA-Interim as having a resolution of 79 km. While it is relatively simple to do

the conversion I would suggest including a ballpark resolution in kilometers for

ERA5, e.g., "The atmospheric variables have a horizontal resolution of 0.25

degrees (~25 km)..."

Lines 108-126: A good chunk of this paragraph could be moved to the

introduction, particularly the description of the history of parametric wind

models. The description of IBTrACS should remain in this section. Alternatively,

as mentioned above, having a separate subsection with each parametric model

described in more detail would be useful.

Line 180: "Tidal amplitudes are relatively moderated in the region..." This is a

little awkward. Perhaps clarify what you mean by "moderated".

Line 213: "This experience is conducted with the ADCIRC..." Should be

"experiment".

Line 235: You say that variables are described, "in the NEMO description part."

Give a section number instead to make it easier to locate where this information

can be found.

These are just some examples of places where I found the readability of this

manuscript to be lacking. I think that some thorough editing will really bring

out the message and findings of the article and make it much more accessible to

the reader.

This manuscript focuses on the performance of NEMO and ADCIRC ocean models in simulating storm surges in tropical east Atlantic. 

It concludes that both ocean models can simulate storm surge in a similar way.

It also concludes that ERA5 atmospheric reanalysis forcing gives better results than parametric wind models and also that inclusion of baroclinic processes in the simulation improves the result significantly. Different wind stress parametrizations, and the surge interaction with tide and mean sea level have shown little to minimal impact.

Globally I would say that this study is well conducted, and gives some interesting results.

However, I would suggest a general review to improve the flow and readability.

Sometimes it gets hard to follow.



I have one specific comment:

In lines 219-230 you describe how you investigated the impact of wind stress parameterizations.

I find this section very hard to follow. I also would say that is poor in terms of content.

I would re-write this part describing both equations in more detail, especially Eq.1, that has no description of the variables whatsoever.

I appreciate the fact that you performed a different simulation with a variable Charnock parameter depending on wave parameters. You should explain why you performed this additional simulation, mentioning why sea roughness is dependent on wave parameters, explaining what variables have an impact, and cite the authors that investigated this process.

Also, I could not find (Smith and Banke, 1975) on your reference list. There could be others missing.

I recommend to check the list very carefully.